Drive assembly with hydraulic actuating mechanism

Abstract

A drive assembly for a motor vehicle driven by a plurality of axles includes a differential unit, an externally controllable hang-on coupling, an externally controllable locking coupling, a first hydraulic actuating unit, and a second hydraulic actuating unit. The differential unit includes an input part that is rotatably drivable around an axis of rotation, and two output parts drivingly connected to the input part. The hang-on coupling drivingly connects the differential unit and a driveshaft. The locking coupling locks the differential movement between the two output parts of the differential assembly. The first hydraulic actuating unit actuates the hang-on coupling and the second hydraulic actuating unit actuates the locking coupling. The first hydraulic actuating unit, the hang-on coupling, the second hydraulic actuating unit and the locking coupling are arranged coaxially relative to the axis of rotation.

The invention claimed is: 
     
       1. A drive assembly for a motor vehicle driven by a plurality of axles, comprising:
 a differential unit with an input part which is rotatably drivable around an axis of rotation by a driveshaft, and two output parts which are drivingly connected to the input part; 
 an externally controllable hang-on coupling which is arranged between the driveshaft and the input part of the differential unit and which serves for optionally drivingly connecting the differential unit and the driveshaft, wherein the differential unit is driven by the driveshaft when the hang-on coupling is closed and non-driven when the hang-on coupling is open; 
 an externally controllable locking coupling for locking a differential movement between the two output parts of the differential unit; 
 a first hydraulic actuating unit for closing the hang-on coupling when a hydraulic pressure is generated; 
 a second hydraulic actuating unit for actuating the locking coupling independently from the hang-on coupling; 
 wherein the first hydraulic actuating unit, the hang-on coupling, the second hydraulic actuating unit and the locking coupling are arranged coaxially relative to the axis of rotation. 
 
     
     
       2. A drive assembly according to  claim 1 , wherein the first hydraulic actuating unit and the second hydraulic actuating unit are supplied with a same amount of hydraulic pressure. 
     
     
       3. A drive assembly according to  claim 1 , wherein there is provided a hydraulic pump which, for generating pressure, is hydraulically connected to the first hydraulic actuating unit as well as to the second hydraulic actuating unit. 
     
     
       4. A drive assembly according to  claim 3 , wherein there is provided an electric motor for driving the pump, wherein the level of the hydraulic pressure is variably settable by the rotation speed of the electric motor. 
     
     
       5. A drive assembly according to  claim 3 , wherein in a connecting channel between the pump and the second hydraulic actuating unit there is provided a switching valve which is switchable between an open position in which hydraulic pressure is transmitted to the second hydraulic actuating unit, and a closed position in which the supply of hydraulic pressure is interrupted. 
     
     
       6. A drive assembly according to  claim 3 , wherein in a connecting channel between the pump and the second hydraulic actuating unit, there is provided a proportional valve which is variably settable between an open position in which hydraulic pressure is transmitted to the second hydraulic actuating unit, and a closed position in which the supply of hydraulic pressure is interrupted. 
     
     
       7. A drive assembly according to  claim 3 , wherein in a connecting channel between the pump and the first hydraulic actuating unit there is provided a proportional valve which is variably settable between an open position in which the hydraulic pressure is transmitted to the first hydraulic actuating unit, and a closed position in which the supply of hydraulic pressure is interrupted. 
     
     
       8. A drive assembly according to  claim 3 , wherein a further switching valve is arranged in a connecting channel between the pump and the first actuating unit and is switchable between an open position in which hydraulic pressure is transmitted to the first actuating unit, and a closed position in which the supply of hydraulic pressure is interrupted. 
     
     
       9. A drive assembly according to  claim 1 , wherein a generatable coupling moment of the hang-on coupling and a generatable coupling moment of the locking coupling have a fixed ratio relative to one another. 
     
     
       10. A drive assembly according to  claim 1 , wherein the hang-on coupling is arranged between the driveshaft and the input part of the differential unit and that the locking coupling is arranged between the input part and one of the output parts of the differential unit. 
     
     
       11. A drive assembly according to  claim 1 , wherein the hang-on coupling is provided in the form of a friction plate coupling, wherein a first plate carrier of the hang-on coupling is connected in a rotationally fixed way to the driveshaft and wherein a second plate carrier of the hang-on coupling is connected in a rotationally fixed way to the input part of the differential unit. 
     
     
       12. A drive assembly according to  claim 1 , wherein, with reference to a central plane of the differential unit, the locking coupling and the hang-on coupling are arranged on the same side. 
     
     
       13. A drive assembly according to  claim 1 , wherein the first hydraulic actuating unit and the second hydraulic actuating unit are arranged axially between the locking coupling and the hang-on coupling. 
     
     
       14. A drive assembly according to  claim 1 , wherein the locking coupling and the hang-on coupling comprise approximately the same friction radius. 
     
     
       15. A drive assembly according to  claim 1 , wherein the hang-on coupling can be loaded by the first hydraulic actuating unit via a first pressure plate and that the locking coupling can be loaded by the second hydraulic actuating unit via a second pressure plate, wherein, when being actuated, the first and the second pressure plate are loaded away from one another. 
     
     
       16. A drive assembly according to  claim 1 , wherein the hang-on coupling and the locking coupling are received in a housing and are each axially supported relative to same. 
     
     
       17. A drive assembly according to  claim 1 , wherein the first hydraulic actuating unit and the second actuating unit are each provided in the form of a piston/cylinder unit.